1. Field of the Invention
The invention relates in general to elevator systems, and more specifically, to new and improved car position indicators for elevator systems.
2. Description of the Prior Art
Elevator systems conventionally provide a car position indicator in each elevator car to indicate to the passengers the position of the elevator car relative to the floors, and a car position indicator may also be located remotely from the car, at a selected floor, or floors, such as at a traffic director's station. The car position displayed on the position indicator is normally the advanced floor position of the car, i.e., the actual position of a stationary car, and the closest floor to the car at which the car could make a normal stop, for a moving car.
With an electromechanical floor selector, the car position indicator is driven by contacts actuated as the floor selector is driven in synchronism with the movement of the elevator car. U.S. Pat. No. 2,085,135 is an example of this type of position indicator. With a solid state floor selector, the advanced floor position may be developed by generating pulses responsive to car movement which are summed to proved a continuous car position, and this signal may be used to provide index pulses for an up-down counter which provides a car position signal related to a floor. U.S. Pat. No. 3,750,850 is an example of a floor selector which generates the advanced car position in this manner.
It is common in tall buildings to have banks of elevator cars which are enabled to serve only certain of the floors. This is usually a permanent arrangement, in which event there are no hoistway doors at the floors which the elevator car passes but which does not serve. When the elevator car is located in a zone of floors which it does not serve, which zone may include 10, 20, or more floors, the car position indicator for this car simply displays an "X", or other suitable symbol, to indicate the car is in an express zone.
It is also common for a structure or a building to have a more than normal spacing between certain of the floors, such as between the lobby floor and the next higher floor, due to a high ceiling in the lobby. The floor selector is constructed to accommodate different distances between the floors, and will usually display the floor number of the floor with the high ceiling as it is traversing the greater than normal floor-to-floor distance.
If an elevator car becomes disabled, there is no problem in quickly locating the car if it is adjacent a floor opening. However, the car may be stopped due to an emergency situation, in which event it may stop without regard to its position relative to a floor level. This may occur due to the operation of any one of many safety and monitoring devices in the elevator system, power failure, earthquake detection, or the like.
When an elevator car is disabled or stuck in the shaftway away from a floor opening, it is a difficult problem to quickly determine the position of the car so that it may be moved to the nearest landing, if possible, or at least to facilitate the evacuation of passengers from the car. The problem may be complicated by greater than normal floor-to-floor heights. If a car is disabled in the express zone of a building, the problem of locating the car becomes significantly more difficult. The express zone might cover a distance of 100, 200, or more feet.
In conventional elevator systems there is generally no easy method for determining the position of an elevator car in an express zone to within the less than 10 feet without entering the machine room. Even then, depending upon the type of floor selector in use, it can be both difficult and time consuming to determine the car position accurately. In the event of an emergency situation, such as an earthquake or a fire, it is extremely important to locate all disabled cars in a minimum amount of time. Also, during the emergency condition, access to the elevator machine room may not be possible. Thus, it would be highly desirable to have means for quickly locating any car which is disabled in the shaftway.